Power Supply Circuits


Low Ohms Adaptor For DMMs Based On An LM317 Regulator

This adaptor circuit is essentially a 100mA constant current source. It is applied across a low-value resistor of unknown value (ie, the resistance to be measured) and the resulting voltage drop can then be measured by a digital multimeter (DMM). Setting your DMM to the 200mV range will enable it to measure up to 2O […]


Drill Speed Regulator

A mini-drill machine is always needed in drilling the printed circuit board. It is usually powered by batteries that limit the drill’s capacity.Using a power supply adaptor with a speed regulator like the one featured here can certainly improve the performance of the drill. The speed regulator can maintain the speed of the drill no […]


Low Ohms Adaptor For DMMs Based On An LM317 Regulator

This adaptor circuit is essentially a 100mA constant current source. It is applied across a low-value resistor of unknown value (ie, the resistance to be measured) and the resulting voltage drop can then be measured by a digital multimeter (DMM). Setting your DMM to the 200mV range will enable it to measure up to 2O […]


Supply Voltage Monitor

A circuit for monitoring supply voltages of ±5 V and ±12 V is readily constructed as shown in the diagram. It is appreciably simpler than the usual monitors that use comparators, and AND gates. The circuit is not intended to indicate the level of the inputs. In normal operation, transistors T1 and T3 must be […]


Supply Voltage Monitor

A circuit for monitoring supply voltages of ±5 V and ±12 V is readily constructed as shown in the diagram. It is appreciably simpler than the usual monitors that use comparators, and AND gates. The circuit is not intended to indicate the level of the inputs. In normal operation, transistors T1 and T3 must be […]


0 to 40V Lab Power Supply

A very lab adjustable power supply that can provide an output voltage between 0 and 60 volts can be designed using this circuit diagram . This lab power supply can be designed with LM723 chip or for higher output voltages, with L146 .Output current is also adjustable, but once established, is always effective. Table 1 […]


0 to 40V Lab Power Supply

A very lab adjustable power supply that can provide an output voltage between 0 and 60 volts can be designed using this circuit diagram . This lab power supply can be designed with LM723 chip or for higher output voltages, with L146 .Output current is also adjustable, but once established, is always effective. Table 1 […]


0V to 50 Volt Variable Regulator

A very simple variable power supply circuit can be made using this electronic circuit diagram .This variable regulator circuit will provide an variable regulated output voltage , between 0 and 50 volts . The CA3140 operational amplifier compares the regulator output to a reference voltage , that depends on the R9 value. 0V to 50 […]


Low Power 12V Transformerless Power Supply

Many circuits can be powered directly from the mains with the aid of a series capacitor (C1). The disadvantage of this approach is that usually only one half cycle of the mains wave-form can be used to produce a DC voltage. An obvious solution is to use a bridge rectifier to perform full-wave rectification, which […]


0V to 50 Volt Variable Regulator

A very simple variable power supply circuit can be made using this electronic circuit diagram .This variable regulator circuit will provide an variable regulated output voltage , between 0 and 50 volts . The CA3140 operational amplifier compares the regulator output to a reference voltage , that depends on the R9 value. 0V to 50 […]